Look, I know this won't help a bit but it's true. 6 years or so ago I had a terrible pain in my back and could not fly for a week or so. I was in agony and had a bit of physiotherapy. When the pain was under control, by use of various exercises, I went back to work. flying A320s. The moment I slouched into the seat all the pain went away. Now, if ever I get a twinge, I can make it go away my self. My posture is as terrible as it ever was but I lead a far more active life. Now I am on boeings again I miss the bus seat but so far so good.